argumentative speech nature vs nurture brainly

• Bipolar Disorder
• Therapy Center
• When To See a Therapist
• Types of Therapy
• Best Online Therapy
• Best Couples Therapy
• Managing Stress
• Sleep and Dreaming
• Understanding Emotions
• Self-Improvement
• Healthy Relationships
• Student Resources
• Personality Types
• Guided Meditations
• Verywell Mind Insights
• 2024 Verywell Mind 25
• Mental Health in the Classroom
• Editorial Process
• Meet Our Review Board
• Crisis Support

The Nature vs. Nurture Debate

Genetic and Environmental Influences and How They Interact

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Verywell / Joshua Seong

• Definitions
• Interaction
• Contemporary Views

Nature refers to how genetics influence an individual's personality, whereas nurture refers to how their environment (including relationships and experiences) impacts their development. Whether nature or nurture plays a bigger role in personality and development is one of the oldest philosophical debates within the field of psychology .

Learn how each is defined, along with why the issue of nature vs. nurture continues to arise. We also share a few examples of when arguments on this topic typically occur, how the two factors interact with each other, and contemporary views that exist in the debate of nature vs. nurture as it stands today.

Nature and Nurture Defined

To better understand the nature vs. nurture argument, it helps to know what each of these terms means.

• Nature refers largely to our genetics . It includes the genes we are born with and other hereditary factors that can impact how our personality is formed and influence the way that we develop from childhood through adulthood.
• Nurture encompasses the environmental factors that impact who we are. This includes our early childhood experiences, the way we were raised , our social relationships, and the surrounding culture.

A few biologically determined characteristics include genetic diseases, eye color, hair color, and skin color. Other characteristics are tied to environmental influences, such as how a person behaves, which can be influenced by parenting styles and learned experiences.

For example, one child might learn through observation and reinforcement to say please and thank you. Another child might learn to behave aggressively by observing older children engage in violent behavior on the playground.

The Debate of Nature vs. Nurture

The nature vs. nurture debate centers on the contributions of genetics and environmental factors to human development. Some philosophers, such as Plato and Descartes, suggested that certain factors are inborn or occur naturally regardless of environmental influences.

Advocates of this point of view believe that all of our characteristics and behaviors are the result of evolution. They contend that genetic traits are handed down from parents to their children and influence the individual differences that make each person unique.

Other well-known thinkers, such as John Locke, believed in what is known as tabula rasa which suggests that the mind begins as a blank slate . According to this notion, everything that we are is determined by our experiences.

Behaviorism is a good example of a theory rooted in this belief as behaviorists feel that all actions and behaviors are the results of conditioning. Theorists such as John B. Watson believed that people could be trained to do and become anything, regardless of their genetic background.

People with extreme views are called nativists and empiricists. Nativists take the position that all or most behaviors and characteristics are the result of inheritance. Empiricists take the position that all or most behaviors and characteristics result from learning.

Examples of Nature vs. Nurture

One example of when the argument of nature vs. nurture arises is when a person achieves a high level of academic success . Did they do so because they are genetically predisposed to elevated levels of intelligence, or is their success a result of an enriched environment?

The argument of nature vs. nurture can also be made when it comes to why a person behaves in a certain way. If a man abuses his wife and kids, for instance, is it because he was born with violent tendencies, or is violence something he learned by observing others in his life when growing up?

Nature vs. Nurture in Psychology

Throughout the history of psychology , the debate of nature vs. nurture has continued to stir up controversy. Eugenics, for example, was a movement heavily influenced by the nativist approach.

Psychologist Francis Galton coined the terms 'nature versus nurture' and 'eugenics' and believed that intelligence resulted from genetics. Galton also felt that intelligent individuals should be encouraged to marry and have many children, while less intelligent individuals should be discouraged from reproducing.

The value placed on nature vs. nurture can even vary between the different branches of psychology , with some branches taking a more one-sided approach. In biopsychology , for example, researchers conduct studies exploring how neurotransmitters influence behavior, emphasizing the role of nature.

In social psychology , on the other hand, researchers might conduct studies looking at how external factors such as peer pressure and social media influence behaviors, stressing the importance of nurture. Behaviorism is another branch that focuses on the impact of the environment on behavior.

Nature vs. Nurture in Child Development

Some psychological theories of child development place more emphasis on nature and others focus more on nurture. An example of a nativist theory involving child development is Chomsky's concept of a language acquisition device (LAD). According to this theory, all children are born with an instinctive mental capacity that allows them to both learn and produce language.

An example of an empiricist child development theory is Albert Bandura's social learning theory . This theory says that people learn by observing the behavior of others. In his famous Bobo doll experiment , Bandura demonstrated that children could learn aggressive behaviors simply by observing another person acting aggressively.

Nature vs. Nurture in Personality Development

There is also some argument as to whether nature or nurture plays a bigger role in the development of one's personality. The answer to this question varies depending on which personality development theory you use.

According to behavioral theories, our personality is a result of the interactions we have with our environment, while biological theories suggest that personality is largely inherited. Then there are psychodynamic theories of personality that emphasize the impact of both.

Nature vs. Nurture in Mental Illness Development

One could argue that either nature or nurture contributes to mental health development. Some causes of mental illness fall on the nature side of the debate, including changes to or imbalances with chemicals in the brain. Genetics can also contribute to mental illness development, increasing one's risk of a certain disorder or disease.

Mental disorders with some type of genetic component include autism , attention-deficit hyperactivity disorder (ADHD), bipolar disorder , major depression , and schizophrenia .

Other explanations for mental illness are environmental. This includes being exposed to environmental toxins, such as drugs or alcohol, while still in utero. Certain life experiences can also influence mental illness development, such as witnessing a traumatic event, leading to the development of post-traumatic stress disorder (PTSD).

Nature vs. Nurture in Mental Health Therapy

Different types of mental health treatment can also rely more heavily on either nature or nurture in their treatment approach. One of the goals of many types of therapy is to uncover any life experiences that may have contributed to mental illness development (nurture).

However, genetics (nature) can play a role in treatment as well. For instance, research indicates that a person's genetic makeup can impact how their body responds to antidepressants. Taking this into consideration is important for getting that person the help they need.

Interaction Between Nature and Nurture

Which is stronger: nature or nurture? Many researchers consider the interaction between heredity and environment—nature with nurture as opposed to nature versus nurture—to be the most important influencing factor of all.

For example, perfect pitch is the ability to detect the pitch of a musical tone without any reference. Researchers have found that this ability tends to run in families and might be tied to a single gene. However, they've also discovered that possessing the gene is not enough as musical training during early childhood is needed for this inherited ability to manifest itself.

Height is another example of a trait influenced by an interaction between nature and nurture. A child might inherit the genes for height. However, if they grow up in a deprived environment where proper nourishment isn't received, they might never attain the height they could have had if they'd grown up in a healthier environment.

A newer field of study that aims to learn more about the interaction between genes and environment is epigenetics . Epigenetics seeks to explain how environment can impact the way in which genes are expressed.

Some characteristics are biologically determined, such as eye color, hair color, and skin color. Other things, like life expectancy and height, have a strong biological component but are also influenced by environmental factors and lifestyle.

Contemporary Views of Nature vs. Nurture

Most experts recognize that neither nature nor nurture is stronger than the other. Instead, both factors play a critical role in who we are and who we become. Not only that but nature and nurture interact with each other in important ways all throughout our lifespan.

As a result, many in this field are interested in seeing how genes modulate environmental influences and vice versa. At the same time, this debate of nature vs. nurture still rages on in some areas, such as in the origins of homosexuality and influences on intelligence .

While a few people take the extreme nativist or radical empiricist approach, the reality is that there is not a simple way to disentangle the multitude of forces that exist in personality and human development. Instead, these influences include genetic factors, environmental factors, and how each intermingles with the other.

Schoneberger T. Three myths from the language acquisition literature . Anal Verbal Behav . 2010;26(1):107-31. doi:10.1007/bf03393086

National Institutes of Health. Common genetic factors found in 5 mental disorders .

Pain O, Hodgson K, Trubetskoy V, et al. Identifying the common genetic basis of antidepressant response . Biol Psychiatry Global Open Sci . 2022;2(2):115-126. doi:10.1016/j.bpsgos.2021.07.008

Moulton C. Perfect pitch reconsidered . Clin Med J . 2014;14(5):517-9 doi:10.7861/clinmedicine.14-5-517

Levitt M. Perceptions of nature, nurture and behaviour . Life Sci Soc Policy . 2013;9:13. doi:10.1186/2195-7819-9-13

Bandura A, Ross D, Ross, SA. Transmission of aggression through the imitation of aggressive models . J Abnorm Soc Psychol. 1961;63(3):575-582. doi:10.1037/h0045925

Chomsky N. Aspects of the Theory of Syntax .

Galton F. Inquiries into Human Faculty and Its Development .

Watson JB. Behaviorism .

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Nature vs. Nurture Debate In Psychology

Saul McLeod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Learn about our Editorial Process

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

On This Page:

The nature vs. nurture debate in psychology concerns the relative importance of an individual’s innate qualities (nature) versus personal experiences (nurture) in determining or causing individual differences in physical and behavioral traits. While early theories favored one factor over the other, contemporary views recognize a complex interplay between genes and environment in shaping behavior and development.

Key Takeaways

• Nature is what we think of as pre-wiring and is influenced by genetic inheritance and other biological factors.
• Nurture is generally taken as the influence of external factors after conception, e.g., the product of exposure, life experiences, and learning on an individual.
• Behavioral genetics has enabled psychology to quantify the relative contribution of nature and nurture concerning specific psychological traits.
• Instead of defending extreme nativist or nurturist views, most psychological researchers are now interested in investigating how nature and nurture interact in a host of qualitatively different ways.
• For example, epigenetics is an emerging area of research that shows how environmental influences affect the expression of genes.

The nature-nurture debate is concerned with the relative contribution that both influences make to human behavior, such as personality, cognitive traits, temperament and psychopathology.

Examples of Nature vs. Nurture

Nature vs. nurture in child development.

In child development, the nature vs. nurture debate is evident in the study of language acquisition . Researchers like Chomsky (1957) argue that humans are born with an innate capacity for language (nature), known as universal grammar, suggesting that genetics play a significant role in language development.

Conversely, the behaviorist perspective, exemplified by Skinner (1957), emphasizes the role of environmental reinforcement and learning (nurture) in language acquisition.

Twin studies have provided valuable insights into this debate, demonstrating that identical twins raised apart may share linguistic similarities despite different environments, suggesting a strong genetic influence (Bouchard, 1979).

However, environmental factors, such as exposure to language-rich environments, also play a crucial role in language development, highlighting the intricate interplay between nature and nurture in child development.

Nature vs. Nurture in Personality Development

The nature vs. nurture debate in personality psychology centers on the origins of personality traits. Twin studies have shown that identical twins reared apart tend to have more similar personalities than fraternal twins, indicating a genetic component to personality (Bouchard, 1994).

However, environmental factors, such as parenting styles, cultural influences, and life experiences, also shape personality.

For example, research by Caspi et al. (2003) demonstrated that a particular gene (MAOA) can interact with childhood maltreatment to increase the risk of aggressive behavior in adulthood.

This highlights that genetic predispositions and environmental factors contribute to personality development, and their interaction is complex and multifaceted.

Nature vs. Nurture in Mental Illness Development

The nature vs. nurture debate in mental health explores the etiology of depression. Genetic studies have identified specific genes associated with an increased vulnerability to depression, indicating a genetic component (Sullivan et al., 2000).

However, environmental factors, such as adverse life events and chronic stress during childhood, also play a significant role in the development of depressive disorders (Dube et al.., 2002; Keller et al., 2007)

The diathesis-stress model posits that individuals inherit a genetic predisposition (diathesis) to a disorder, which is then activated or exacerbated by environmental stressors (Monroe & Simons, 1991).

This model illustrates how nature and nurture interact to influence mental health outcomes.

Nature vs. Nurture of Intelligence

The nature vs. nurture debate in intelligence examines the relative contributions of genetic and environmental factors to cognitive abilities.

Intelligence is highly heritable, with about 50% of the variance in IQ attributed to genetic factors, based on studies of twins, adoptees, and families (Plomin & Spinath, 2004).

Heritability of intelligence increases with age, from about 20% in infancy to as high as 80% in adulthood, suggesting amplifying effects of genes over time.

However, environmental influences, such as access to quality education and stimulating environments, also significantly impact intelligence.

Shared environmental influences like family background are more influential in childhood, whereas non-shared experiences are more important later in life.

Research by Flynn (1987) showed that average IQ scores have increased over generations, suggesting that environmental improvements, known as the Flynn effect , can lead to substantial gains in cognitive abilities.

Molecular genetics provides tools to identify specific genes and understand their pathways and interactions. However, progress has been slow for complex traits like intelligence. Identified genes have small effect sizes (Plomin & Spinath, 2004).

Overall, intelligence results from a complex interplay between genes and environment over development. Molecular genetics offers promise to clarify these mechanisms. The nature vs nurture debate is outdated – both play key roles.

Nativism (Extreme Nature Position)

It has long been known that certain physical characteristics are biologically determined by genetic inheritance.

Color of eyes, straight or curly hair, pigmentation of the skin, and certain diseases (such as Huntingdon’s chorea) are all a function of the genes we inherit.

These facts have led many to speculate as to whether psychological characteristics such as behavioral tendencies, personality attributes, and mental abilities are also “wired in” before we are even born.

Those who adopt an extreme hereditary position are known as nativists.  Their basic assumption is that the characteristics of the human species as a whole are a product of evolution and that individual differences are due to each person’s unique genetic code.

In general, the earlier a particular ability appears, the more likely it is to be under the influence of genetic factors. Estimates of genetic influence are called heritability.

Examples of extreme nature positions in psychology include Chomsky (1965), who proposed language is gained through the use of an innate language acquisition device. Another example of nature is Freud’s theory of aggression as being an innate drive (called Thanatos).

Characteristics and differences that are not observable at birth, but which emerge later in life, are regarded as the product of maturation. That is to say, we all have an inner “biological clock” which switches on (or off) types of behavior in a pre-programmed way.

The classic example of the way this affects our physical development is the bodily changes that occur in early adolescence at puberty.

However, nativists also argue that maturation governs the emergence of attachment in infancy , language acquisition , and even cognitive development .

Empiricism (Extreme Nurture Position)

At the other end of the spectrum are the environmentalists – also known as empiricists (not to be confused with the other empirical/scientific approach ).

Their basic assumption is that at birth, the human mind is a tabula rasa (a blank slate) and that this is gradually “filled” as a result of experience (e.g., behaviorism ).

From this point of view, psychological characteristics and behavioral differences that emerge through infancy and childhood are the results of learning.  It is how you are brought up (nurture) that governs the psychologically significant aspects of child development and the concept of maturation applies only to the biological.

For example, Bandura’s (1977) social learning theory states that aggression is learned from the environment through observation and imitation. This is seen in his famous Bobo doll experiment (Bandura, 1961).

Also, Skinner (1957) believed that language is learned from other people via behavior-shaping techniques.

Evidence for Nature

• Biological Approach
• Biology of Gender
• Medical Model

Freud (1905) stated that events in our childhood have a great influence on our adult lives, shaping our personality.

He thought that parenting is of primary importance to a child’s development , and the family as the most important feature of nurture was a common theme throughout twentieth-century psychology (which was dominated by environmentalists’ theories).

Behavioral Genetics

Researchers in the field of behavioral genetics study variation in behavior as it is affected by genes, which are the units of heredity passed down from parents to offspring.

“We now know that DNA differences are the major systematic source of psychological differences between us. Environmental effects are important but what we have learned in recent years is that they are mostly random – unsystematic and unstable – which means that we cannot do much about them.” Plomin (2018, xii)

Behavioral genetics has enabled psychology to quantify the relative contribution of nature and nurture with regard to specific psychological traits. One way to do this is to study relatives who share the same genes (nature) but a different environment (nurture). Adoption acts as a natural experiment which allows researchers to do this.

Empirical studies have consistently shown that adoptive children show greater resemblance to their biological parents, rather than their adoptive, or environmental parents (Plomin & DeFries, 1983; 1985).

Another way of studying heredity is by comparing the behavior of twins, who can either be identical (sharing the same genes) or non-identical (sharing 50% of genes). Like adoption studies, twin studies support the first rule of behavior genetics; that psychological traits are extremely heritable, about 50% on average.

The Twins in Early Development Study (TEDS) revealed correlations between twins on a range of behavioral traits, such as personality (empathy and hyperactivity), and components of reading such as phonetics (Haworth, Davis, Plomin, 2013; Oliver & Plomin, 2007; Trouton, Spinath, & Plomin, 2002).

Implications

Jenson (1969) found that the average I.Q. scores of black Americans were significantly lower than whites he went on to argue that genetic factors were mainly responsible – even going so far as to suggest that intelligence is 80% inherited.

The storm of controversy that developed around Jenson’s claims was not mainly due to logical and empirical weaknesses in his argument. It had more to do with the social and political implications that are often drawn from research that claims to demonstrate natural inequalities between social groups.

For many environmentalists, there is a barely disguised right-wing agenda behind the work of behavioral geneticists.  In their view, part of the difference in the I.Q. scores of different ethnic groups is due to inbuilt biases in the methods of testing.

More fundamentally, they believe that differences in intellectual ability are a product of social inequalities in access to material resources and opportunities.  To put it simply children brought up in the ghetto tend to score lower on tests because they are denied the same life chances as more privileged members of society.

Now we can see why the nature-nurture debate has become such a hotly contested issue.  What begins as an attempt to understand the causes of behavioral differences often develops into a politically motivated dispute about distributive justice and power in society.

What’s more, this doesn’t only apply to the debate over I.Q.  It is equally relevant to the psychology of sex and gender , where the question of how much of the (alleged) differences in male and female behavior are due to biology and how much to culture is just as controversial.

Polygenic Inheritance

Rather than the presence or absence of single genes being the determining factor that accounts for psychological traits, behavioral genetics has demonstrated that multiple genes – often thousands, collectively contribute to specific behaviors.

Thus, psychological traits follow a polygenic mode of inheritance (as opposed to being determined by a single gene). Depression is a good example of a polygenic trait, which is thought to be influenced by around 1000 genes (Plomin, 2018).

This means a person with a lower number of these genes (under 500) would have a lower risk of experiencing depression than someone with a higher number.

While still limited in predictive power, polygenic risk scores provide a way to quantify innate genetic risk, allowing researchers to study how this interacts with environmental factors to influence outcomes.

The high polygenicity of psychiatric disorders (many genes each contributing small effects) revealed by genetic architecture studies shows that there isn’t a simple genetic determinism for most psychiatric conditions. 

This complexity is further increased when you consider how these genes might interact with each other (epistasis) and with environmental factors. The same genetic profile might lead to different outcomes in different environments.

The Nature of Nurture

Nurture assumes that correlations between environmental factors and psychological outcomes are caused environmentally. For example, how much parents read with their children and how well children learn to read appear to be related. Other examples include environmental stress and its effect on depression.

However, behavioral genetics argues that what looks like environmental effects are to a large extent a reflection of genetic differences (Plomin & Bergeman, 1991).

People select, modify, and create environments correlated with their genetic disposition. This means that what sometimes appears to be an environmental influence (nurture) is a genetic influence (nature).

So, children genetically predisposed to be competent readers will be happy to listen to their parents read them stories, and be more likely to encourage this interaction.

Interaction Effects

However, in recent years there has been a growing realization that the question of “how much” behavior is due to heredity and “how much” to the environment may itself be the wrong question.

Take intelligence as an example. Like almost all types of human behavior, it is a complex, many-sided phenomenon that reveals itself (or not!) in a great variety of ways.

The “how much” question assumes that psychological traits can all be expressed numerically and that the issue can be resolved in a quantitative manner.

Heritability statistics revealed by behavioral genetic studies have been criticized as meaningless, mainly because biologists have established that genes cannot influence development independently of environmental factors; genetic and nongenetic factors always cooperate to build traits.

The reality is that nature and culture interact in a myriad of qualitatively different ways (Gottlieb, 2007; Johnston & Edwards, 2002).

Instead of defending extreme nativist or nurturist views, most psychological researchers are now interested in investigating how nature and nurture interact.

For example, in psychopathology , this means that both a genetic predisposition and an appropriate environmental trigger are required for a mental disorder to develop. 

This concept, known as the diathesis-stress model, suggests that individuals may inherit a vulnerability to certain mental health conditions, but the actual manifestation of these disorders frequently depends on exposure to specific environmental stressors.

• Diathesis : Some individuals have a genetic vulnerability (predisposition) to certain mental disorders.
• Stress : Environmental factors or life events act as triggers.
• Interaction : The combination of genetic vulnerability and environmental stress leads to the manifestation of a disorder.

For instance, a person might carry genes associated with depression, but may not develop the disorder unless exposed to significant life stressors, trauma, or adverse experiences.

Furthermore, the emerging field of epigenetics provides additional insight into this complex relationship.

What is Epigenetics?

Epigenetics is the term used to describe inheritance by mechanisms other than through the DNA sequence of genes. For example, features of a person’s physical and social environment can effect which genes are switched-on, or “expressed”, rather than the DNA sequence of the genes themselves.

Epigenetics refers to changes in gene expression that don’t involve alterations to the DNA sequence itself. Instead, these changes affect how genes are read and translated into proteins.

Basic Explanation

Imagine your DNA as a huge instruction manual for your body. Epigenetics is like highlighters and sticky notes added to this manual.

These markers don’t change the actual text (your DNA), but they can make certain instructions easier or harder to read. Things in your environment, like what you eat, how stressed you are, or even your experiences, can add or remove these markers.

This process can turn genes “on” or “off,” affecting how your body works. Sometimes, these changes can even be passed down to your kids, kind of like inherited highlighter marks in the manual.

Mechanisms of Epigenetic Modification

Epigenetic modifications provide a direct biological mechanism by which environmental experiences (nurture) can alter how our genes (nature) function. This challenges the idea of genes as a fixed, unchangeable blueprint.

Epigenetic changes can occur throughout life, but certain periods (like early development or adolescence) may be particularly sensitive to these modifications.

There are several ways epigenetic changes can occur:

• DNA methylation : Adding methyl groups to DNA, typically suppressing gene expression.
• Histone modification : Changes to the proteins that DNA wraps around, affecting how tightly or loosely genes are packaged.
• Non-coding RNA : RNA molecules that can regulate gene expression.

These epigenetic changes can be temporary or long-lasting, and in some cases, may even be heritable.

Example : Early life stress has been shown to cause epigenetic changes in genes related to stress response, potentially increasing vulnerability to stress-related disorders later in life.

Environmental Stressors

Environmental stressors have been shown to induce epigenetic changes, with substantial evidence from both animal and human studies (Klengel et al., 2016).

These stressors can include malnutrition, exposure to toxins, extreme stress, or trauma, leading to alterations in DNA methylation patterns, histone modifications, and changes in non-coding RNA expression (Bale, 2015).

For instance, research has demonstrated that early life stress can result in long-lasting epigenetic modifications of genes involved in stress response pathways, potentially increasing vulnerability to stress-related disorders later in life (McGowan et al., 2009).

Maternal care in rats has been linked to epigenetic changes in offspring, affecting their stress reactivity (Weaver et al., 2004).

In humans, studies of Holocaust survivors and their descendants have revealed epigenetic alterations associated with trauma exposure, suggesting potential transgenerational effects (Yehuda et al., 2016).

These findings underscore the profound impact of environmental factors on gene expression and highlight the plasticity of our epigenome in response to external influences (Szyf, 2011).

Transgenerational Epigenetic Inheritance

Some epigenetic modifications may be passed down to future generations, suggesting that environmental influences on one generation could affect the genetic expression of subsequent generations.

One such example is what is known as the Dutch Hunger Winter, during last year of the Second World War. What they found was that children who were in the womb during the famine experienced a life-long increase in their chances of developing various health problems compared to children conceived after the famine.

Epigenetic effects can sometimes be passed from one generation to the next, although the effects only seem to last for a few generations. There is some evidence that the effects of the Dutch Hunger Winter affected grandchildren of women who were pregnant during the famine.

Therefore, it makes more sense to say that the difference between two people’s behavior is mostly due to hereditary factors or mostly due to environmental factors.

This realization is especially important given the recent advances in genetics, such as polygenic testing.  The Human Genome Project, for example, has stimulated enormous interest in tracing types of behavior to particular strands of DNA located on specific chromosomes.

If these advances are not to be abused, then there will need to be a more general understanding of the fact that biology interacts with both the cultural context and the personal choices that people make about how they want to live their lives.

There is no neat and simple way of unraveling these qualitatively different and reciprocal influences on human behavior.

The Concept of “Memories” Being Passed Down

While there’s evidence that environmental stressors can induce epigenetic changes that might affect future generations, the concept of specific “memories” being passed down is not supported by current scientific evidence.

This concept often stems from misinterpretation of studies showing behavioral or physiological changes in offspring related to parental experiences.

Some animal studies have demonstrated that offspring of stressed parents exhibit altered stress responses or behavioral changes.

For example, Dias and Ressler (2014) showed in mice that fear responses to specific odors can be passed down to subsequent generations. However, these are not “memories” in the conventional sense, but rather alterations in stress response systems or sensory sensitivities.

Human studies in this area are much more complex and limited. Research has examined children of trauma survivors (e.g., Holocaust survivors, 9/11 survivors) and found differences in stress hormone levels or risk for PTSD (Yehuda et al., 2016).

However, these studies face significant challenges in separating genetic, epigenetic, and social/cultural factors.

The challenges in interpreting human studies are substantial. Humans have complex social structures and cultural transmission of information, making it often impossible to separate the effects of biological inheritance from social learning and shared environments (Heard & Martienssen, 2014).

The longer lifespan and generation time in humans also make it challenging to study transgenerational effects. What’s often observed is not the transmission of specific memories, but rather altered predispositions or sensitivities.

For example, children of trauma survivors might have an altered stress response system, making them more sensitive to stress, but they don’t inherit specific memories of the trauma (Bowers & Yehuda, 2016).

While specific memories aren’t passed down, changes in gene expression related to stress response systems could potentially be inherited. These could affect how future generations respond to stress or process sensory information (Zannas et al., 2015).

Epigenetics: Licking Rat Pups

Michael Meaney and his colleagues at McGill University in Montreal, Canada conducted the landmark epigenetic study on mother rats licking and grooming their pups.

This research found that the amount of licking and grooming received by rat pups during their early life could alter their epigenetic marks and influence their stress responses in adulthood.

Pups that received high levels of maternal care (i.e., more licking and grooming) had a reduced stress response compared to those that received low levels of maternal care.

Meaney’s work with rat maternal behavior and its epigenetic effects has provided significant insights into the understanding of early-life experiences, gene expression, and adult behavior.

It underscores the importance of the early-life environment and its long-term impacts on an individual’s mental health and stress resilience.

Epigenetics: The Agouti Mouse Study

Waterland and Jirtle’s 2003 study on the Agouti mouse is another foundational work in the field of epigenetics that demonstrated how nutritional factors during early development can result in epigenetic changes that have long-lasting effects on phenotype.

In this study, they focused on a specific gene in mice called the Agouti viable yellow (A^vy) gene. Mice with this gene can express a range of coat colors, from yellow to mottled to brown.

This variation in coat color is related to the methylation status of the A^vy gene: higher methylation is associated with the brown coat, and lower methylation with the yellow coat.

Importantly, the coat color is also associated with health outcomes, with yellow mice being more prone to obesity, diabetes, and tumorigenesis compared to brown mice.

Waterland and Jirtle set out to investigate whether maternal diet, specifically supplementation with methyl donors like folic acid, choline, betaine, and vitamin B12, during pregnancy could influence the methylation status of the A^vy gene in offspring.

Key findings from the study include:

Dietary Influence : When pregnant mice were fed a diet supplemented with methyl donors, their offspring had an increased likelihood of having the brown coat color. This indicated that the supplemented diet led to an increased methylation of the A^vy gene.

Health Outcomes : Along with the coat color change, these mice also had reduced risks of obesity and other health issues associated with the yellow phenotype.

Transgenerational Effects : The study showed that nutritional interventions could have effects that extend beyond the individual, affecting the phenotype of the offspring.

The implications of this research are profound. It highlights how maternal nutrition during critical developmental periods can have lasting effects on offspring through epigenetic modifications, potentially affecting health outcomes much later in life.

The study also offers insights into how dietary and environmental factors might contribute to disease susceptibility in humans.

Challenges in Epigenetic Research:

• Epigenetic changes can be tissue-specific, making it challenging to study in the living human brain
• The causal direction (whether epigenetic changes cause disorders or result from them) is often unclear
• The complexity of interactions between multiple epigenetic mechanisms and genetic variants

Bale, T. L. (2015). Epigenetic and transgenerational reprogramming of brain development. Nature Reviews Neuroscience, 16 (6), 332-344.

Bandura, A. Ross, D., & Ross, S. A. (1961). Transmission of aggression through the imitation of aggressive models. Journal of Abnormal and Social Psychology , 63, 575-582

Bandura, A. (1977). Social learning theory . Englewood Cliffs, NJ: Prentice Hall.

Bouchard, T. J. (1994). Genes, Environment, and Personality. Science, 264 (5166), 1700-1701.

Bowers, M. E., & Yehuda, R. (2016). Intergenerational transmission of stress in humans. Neuropsychopharmacology, 41 (1), 232-244.

Bowlby, J. (1969). Attachment. Attachment and loss: Vol. 1. Loss . New York: Basic Books.

Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H., … & Poulton, R. (2003). Influence of life stress on depression: moderation by a polymorphism in the 5-HTT gene.  Science ,  301 (5631), 386-389.

Chomsky, N. (1957). Syntactic structures. Mouton de Gruyter.

Chomsky, N. (1965). Aspects of the theory of syntax . MIT Press.

Dias, B. G., & Ressler, K. J. (2014). Parental olfactory experience influences behavior and neural structure in subsequent generations. Nature neuroscience, 17( 1), 89-96.

Dube, S. R., Anda, R. F., Felitti, V. J., Edwards, V. J., & Croft, J. B. (2002). Adverse childhood experiences and personal alcohol abuse as an adult.  Addictive Behaviors ,  27 (5), 713-725.

Flynn, J. R. (1987). Massive IQ gains in 14 nations: What IQ tests really measure.  Psychological Bulletin ,  101 (2), 171.

Freud, S. (1905). Three essays on the theory of sexuality . Se, 7.

Galton, F. (1883). Inquiries into human faculty and its development . London: J.M. Dent & Co.

Gottlieb, G. (2007). Probabilistic epigenesis.   Developmental Science, 10 , 1–11.

Haworth, C. M., Davis, O. S., & Plomin, R. (2013). Twins Early Development Study (TEDS): a genetically sensitive investigation of cognitive and behavioral development from childhood to young adulthood . Twin Research and Human Genetics, 16(1) , 117-125.

Heard, E., & Martienssen, R. A. (2014). Transgenerational epigenetic inheritance: myths and mechanisms. Cell, 157 (1), 95-109.

Horsthemke, B. (2018). A critical view on transgenerational epigenetic inheritance in humans. Nature communications, 9 (1), 1-4.

Jensen, A. R. (1969). How much can we boost I.Q. and scholastic achievement? Harvard Educational Review, 33 , 1-123.

Johnston, T. D., & Edwards, L. (2002). Genes, interactions, and the development of behavior . Psychological Review , 109, 26–34.

Keller, M. C., Neale, M. C., & Kendler, K. S. (2007). Association of different adverse life events with distinct patterns of depressive symptoms.  American Journal of Psychiatry ,  164 (10), 1521-1529.

Klengel, T., Dias, B. G., & Ressler, K. J. (2016). Models of intergenerational and transgenerational transmission of risk for psychopathology in mice. Neuropsychopharmacology, 41 (1), 219-231.

McGowan, P. O., Sasaki, A., D’Alessio, A. C., Dymov, S., Labonté, B., Szyf, M., … & Meaney, M. J. (2009). Epigenetic regulation of the glucocorticoid receptor in human brain associates with childhood abuse. Nature Neuroscience, 12(3), 342-348.

Meaney, M. J. (2010). Epigenetics and the biological definition of gene× environment interactions. Child development, 81 (1), 41-79.

Monroe, S. M., & Simons, A. D. (1991). Diathesis-stress theories in the context of life stress research: implications for the depressive disorders.  Psychological Bulletin ,  110 (3), 406.

Oliver, B. R., & Plomin, R. (2007). Twins” Early Development Study (TEDS): A multivariate, longitudinal genetic investigation of language, cognition and behavior problems from childhood through adolescence . Twin Research and Human Genetics, 10(1) , 96-105.

Petrill, S. A., Plomin, R., Berg, S., Johansson, B., Pedersen, N. L., Ahern, F., & McClearn, G. E. (1998). The genetic and environmental relationship between general and specific cognitive abilities in twins age 80 and older.  Psychological Science ,  9 (3), 183-189.

Plomin, R., & Petrill, S. A. (1997). Genetics and intelligence: What’s new?.  Intelligence ,  24 (1), 53-77.

Plomin, R. (2018). Blueprint: How DNA makes us who we are . MIT Press.

Plomin, R., & Bergeman, C. S. (1991). The nature of nurture: Genetic influence on “environmental” measures. behavioral and Brain Sciences, 14(3) , 373-386.

Plomin, R., & DeFries, J. C. (1983). The Colorado adoption project. Child Development , 276-289.

Plomin, R., & DeFries, J. C. (1985). The origins of individual differences in infancy; the Colorado adoption project. Science, 230 , 1369-1371.

Plomin, R., & Spinath, F. M. (2004). Intelligence: genetics, genes, and genomics.  Journal of personality and social psychology ,  86 (1), 112.

Plomin, R., & Von Stumm, S. (2018). The new genetics of intelligence.  Nature Reviews Genetics ,  19 (3), 148-159.

Skinner, B. F. (1957). Verbal behavior . Acton, MA: Copley Publishing Group.

Sullivan, P. F., Neale, M. C., & Kendler, K. S. (2000). Genetic epidemiology of major depression: review and meta-analysis.  American Journal of Psychiatry ,  157 (10), 1552-1562.

Szyf, M., Weaver, I. C., Champagne, F. A., Diorio, J., & Meaney, M. J. (2005). Maternal programming of steroid receptor expression and phenotype through DNA methylation in the rat .  Frontiers in neuroendocrinology ,  26 (3-4), 139-162.

Trouton, A., Spinath, F. M., & Plomin, R. (2002). Twins early development study (TEDS): a multivariate, longitudinal genetic investigation of language, cognition and behavior problems in childhood . Twin Research and Human Genetics, 5(5) , 444-448.

Waterland, R. A., & Jirtle, R. L. (2003). Transposable elements: targets for early nutritional effects on epigenetic gene regulation . Molecular and cellular biology, 23 (15), 5293-5300.

Weaver, I. C., Cervoni, N., Champagne, F. A., D’Alessio, A. C., Sharma, S., Seckl, J. R., … & Meaney, M. J. (2004). Epigenetic programming by maternal behavior. Nature Neuroscience, 7(8), 847-854.

Yehuda, R., Daskalakis, N. P., Bierer, L. M., Bader, H. N., Klengel, T., Holsboer, F., & Binder, E. B. (2016). Holocaust exposure induced intergenerational effects on FKBP5 methylation. Biological psychiatry, 80(5), 372-380.

Zannas, A. S., Wiechmann, T., Gassen, N. C., & Binder, E. B. (2016). Gene–stress–epigenetic regulation of FKBP5: clinical and translational implications. Neuropsychopharmacology, 41 (1), 261-274.

Further Information

• Genetic & Environmental Influences on Human Psychological Differences

Evidence for Nurture

• Classical Conditioning
• Little Albert Experiment
• Operant Conditioning
• Behaviorism
• Social Learning Theory
• Bronfenbrenner’s Ecological Systems Theory
• Social Roles
• Attachment Styles
• The Hidden Links Between Mental Disorders
• Visual Cliff Experiment
• Behavioral Genetics, Genetics, and Epigenetics
• Epigenetics
• Is Epigenetics Inherited?
• Physiological Psychology
• Bowlby’s Maternal Deprivation Hypothesis
• So is it nature not nurture after all?

Evidence for an Interaction

• Genes, Interactions, and the Development of Behavior
• Agouti Mouse Study
• Biological Psychology

What does nature refer to in the nature vs. nurture debate?

In the nature vs. nurture debate, “nature” refers to the influence of genetics, innate qualities, and biological factors on human development, behavior, and traits. It emphasizes the role of hereditary factors in shaping who we are.

What does nurture refer to in the nature vs. nurture debate?

In the nature vs. nurture debate, “nurture” refers to the influence of the environment, upbringing, experiences, and social factors on human development, behavior, and traits. It emphasizes the role of external factors in shaping who we are.

Why is it important to determine the contribution of heredity (nature) and environment (nurture) in human development?

Determining the contribution of heredity and environment in human development is crucial for understanding the complex interplay between genetic factors and environmental influences. It helps identify the relative significance of each factor, informing interventions, policies, and strategies to optimize human potential and address developmental challenges.